1. Field of Invention
This invention relates to an automotive vehicle test fixture. In particular, the invention relates specifically to a fixture to conduct dynamic, repeatable, controlled destructive rollover impact tests of both full scale vehicles and representations to evaluate strength and occupant protection characteristics of the vehicle roof and other vehicle components. The invention provides precise control of initial test parameters including drop height, contact roll rate, contact roll angle, pitch angle, yaw angle, post contact freefall height, vehicle moment of inertia, roadway surface conditions including friction and impact obstructions. In addition, the invention enables the measurement of dynamic forces and orientations between vehicle and road bed and enables multiple tests to be conducted and evaluated on an isolated singular roll-by-roll basis.
2. Description of Prior Art
Rollovers have been and continue to be a significant cause of occupant fatalities and serious injuries. To date, the experiments to determine vehicle performance have been criticized as unrepeatable and, thus, inappropriate for vehicle or component design and testing and/or compliance type testing. Various other test fixtures have been developed that addresses some of these issues, but require a large infrastructure to run and do not fully control the vehicle after the first impact and during the test (reference: U.S. Pat. No. 6,651,482). Another device (reference U.S. Pat. No. 6,256,601) articulates about a pivot but does not provide a full rollover capability, nor does it provide a means to simulate a roll about the true roll axis of a vehicle. In addition, none of the other test methods allow for the direct measurement of the loads applied to the vehicle, which are important to evaluating and understanding the dynamics of a rollover event. This subject invention resolves these issues in a manner that will allow effective repeatable vehicle testing. Vehicle testing in the rollover regime is crucial to understanding interactions between the occupant and the vehicle's structures, restraints, glazing, etc. A better knowledge of these parameters will allow for improved vehicle designs and a safer vehicle fleet.
Previous testing to determine vehicle performance and vehicle to occupant interactions in rollover conditions uses various types of tests including dropping a rotating vehicle, launching a vehicle from a dolly, launching a vehicle from a ramp or otherwise tripping a vehicle to initiate a roll. The major drawback of these tests is the unrepeatable nature of the testing. While these tests will allow insight into vehicle performance, they do not allow a study of vehicle and component performance during an impact that can be exactly repeated to determine changes in vehicle structure or geometry through repeated tests. In particular, earlier test methods do not result in consistent impacts due to variations in tire to dolly or tire to road impacts before the roof structure interaction or are not controlled after the roof impacts. By controlling the vehicle both before and after the roof impacts, performance during an impact can be isolated and examined in detail.
U.S. Pat. No. 6,651,482 describes an alternate method of rollover testing. The method described in that patent is considerably different from the invention discussed herein. These differences lead to several shortcomings in the previous methodology including the inability to measure the direct forces on the roof of the vehicle, the inability to control the vehicle after the desired roof contacts, the artificial positioning of anthropomorphic crash test dummies if included, the inability of the system to directly determine the roof crush from the desired impact, the inability to evaluate damage on a per roll and/or cumulative basis.
U.S. Pat. No. 6,256,601 describes a rollover test sled designed to simulate the behavior of vehicle occupant and safety systems in a rollover accident. The method described differs significantly from the invention presented herein since the test does not provide the means to rotate a test vehicle or dummies about a roll axis. The fixture described also does not provide the means to rotate the test vehicle for the purposes to measure and evaluate vehicle structural integrity.
Prior art systems are not presently able to provide control of the vehicle in pitch and yaw at the initiation of and during test sequences.
U.S. application Ser. No. 11/380,862 entitled Vehicle Rollover Crash Test Fixture now U.S. Pat. No. 7,373,801 having common inventors with the present application provides a test fixture for repeatable dynamic vehicle rollover testing. The invention disclosed therein provides a moving sled with a contact surface simulating a roadway or other appropriate medium. A cradle to suspend a test vehicle is equipped to rotate and release the vehicle onto the contact surface to repeatably simulate a rollover condition. While coupled motion of the sled and rotation of the vehicle prior to impact provide repeatable test results with highly accurate simulation, the structural and system requirements for creating and coordinating the moving sled contact zone are complex and costly. It is therefore desirable to provide a rollover test fixture with the capabilities of the prior system but simplified to reduce cost, complexity and simulation error as well as ease of setup and safety of operating personnel.
The present invention addresses these issues and provides a simplified and improved dynamic, repeatable vehicle rollover test fixture.